Wow, 70 years young! Congratulations Brian and welcome to Subsim!
It sounds like you're having an issue unzipping the MEP file. If that's the case was there any kind of a pop-up or error message? If not, perhaps it unzipped in a different location.
You could always try again using the 'Extract Here' option. If it still doesn't work re-download the file as the one you have might be corrupt.
Good luck and hope to see you on the high seas soon!